Pulsed radar may be optimally suited for meteorological phenomenon detection, such as rain, turbulence, wind shear, etc. However, for non-weather modes of operation, pulsed radar may have certain limitations concerning minimum range restrictions due to the two-way radar-to-target pulsed format and radar-to-target-to-radar propagation time. Continuous wave radar or Frequency Modulated Continuous Wave (FMCW) may be well suited to close range and moving target reception due to the continuous wave and detail resolution nature of the signal.
A radar system employing an Active Electronically Scanned Antenna (AESA) may be beneficial to users as the size weight power and cost (SWP-C) of such antenna arrays are increasingly efficient for incorporation by the operator.
Radar application modes of critical importance to an operator may include aircraft low visibility taxi operation including operations suited for Surface Movement Guidance and Control System (SMGCS) standards. In such an environment, an operator may be required to monitor and maintain clearance in the area 200-300 feet in front of the operators own aircraft position. Goals of aircraft operators may include a non-cooperative collision avoidance system for such short range threats and an ability for an aircraft to image or perceive close in obstacles i.e., taxiway lights, runway lights and signage, other aircraft and the like. A Radar Cross Section (RCS) on the order of one square meter (1 m2) may be a desired target size for an onboard radar system to image. Additional goals of an onboard system may include an ability to accurately image such a 1 m2 target within 300 feet at a speed of 20 knots (kts) as the target makes a 90 degree turn. Traditional FMCW radar may be better suited for these shorter range goals.
Additionally, challenges remain for operators of a rotary wing aircraft to image such short range targets. A short range capability (e.g. less than 100 feet of range) may enable a rotary wing aircraft to navigate in situations previously prohibited (e.g., sand storms, low visibility launch/recovery operations). Also, during low altitude operations, an ability to image an obstacle, a terrain feature, or a station keeping reference point may enhance rotary wing low altitude capabilities. In these situations, traditional radar may experience “brownout” or a return of unusable significance to an operator due to particular atmospheric conditions. Traditionally, a FMCW radar may be better suited for such a short range solution than would be a pulsed radar.
Previous attempts of solving the problems described above may include Laser Radar (LIDAR) and infrared (IR) systems attempting to image an obstacle or target through a certain atmospheric condition. Both of these attempts may suffer from propagation loss sue to an inability to penetrate the particular atmospheric condition (e.g., blowing sand).
FMCW, however, has limitations considering long range radar solutions for imaging small RCS target (e.g. small aircraft, weather) detection. Pulsed radar may provide a better picture of longer range contacts.
Mounting two types of radar on an airframe may be prohibitively expensive and may be too heavy for adequate performance. A well-known pulsed radar mounted on the forward nose of an aircraft may contribute a significant portion to the overall weight and internal volume of the aircraft. An additional FMCW radar mounted to the same aircraft may encumber electrical and thermal management systems, challenge designers for proper placement, and negatively impact performance.
Multi-chip modes of semiconductor dies may be well-known in the art of semiconductor technology. Semiconductor chips have been organized and placed in a variety of geometries and stacks as mounted on a circuit board substrate. However, the use of Multi-chip modes to overcome the challenges herein has yet to be realized.
Consequently, a need exists for development of an AESA-based hybrid system able to merge pulsed and FMCW elements into a single AESA antenna system specifically capable to solve both short range and long range solutions.